Production machining equipment using endless abrasive belts are presently being used for the preparation and finishing of metallic parts, including cast aluminum parts and cast iron parts, as well as a host of others, with the abrasive belts being used for both grinding and finishing operations. The utilization of such equipment with abrasive belts provides a finished part which is both dimensionally accurate and has a desirable finished surface. The apparatus of the present invention finds application with endless abrasive belts driven at high rates of speed, and provide advantages in use, particularly from the standpoint of high production rates, as well as the preparation of parts having relatively accurate finished dimensions, a high degree of flatness, and a surface with desirable characteristics. In addition to use with metals, the apparatus of the present invention is also adapted for use with other structural materials such as wood.
In the past, and in connection with production machining, various techniques have been employed to control the disposition of a workpiece while held within a working station. In the apparatus of the present invention, however, means are provided for precisely adjusting the position of the working surface of an endless abrasive belt relative to the surface of the workpiece being treated while the workpiece is being held within the working station. This precise adjustment feature is achieved by virtue of a system which controllably advances and retracts the platen or contact drum carrying the working surface of the belt while maintaining the working force substantially constant. The motion of the platen or contact drum is undertaken in response to programmed or controlled input signals. Thus, in addition to controlling the disposition of the work-contacting surface of the belt, the system maintains a substantially constant working force or bias to normally drive the belt back-up means against or toward the working station.
As an added feature, and in order to enhance and maintain accuracy in the grinding and/or finishing operations, means are provided to constantly monitor the position of the belt back-up means in order to compensate and accommodate for the inevitable occurrence of belt wear.